https://www.newyorker.com/culture/annals-of-inquiry/we-know-less-about-social-media-than-we-think
Social media use and youth mental health is in the news again with the congressional hearings. Gonna post this excellent New Yorker piece on the subject. People like James Steyer and Jonathan Haidt are a bit out over their skis on the strength of the available evidence.
And notably Haidt's colleagues disagree with many of his stronger claims. The APA and the AAP both note there isn't yet a causal link between social media use and child mental health. Social media use may be both beneficial and harmful to children, so as with many things there are tradeoffs.